In a mobile radio system, a plurality of users share the same radio channel group. In setting up a call, the system checks the rights of use of the particular subscriber and allocates thereto radio channel capacity by automatically selecting therefor an available radio channel. If the called subscriber is busy or all radio channels are busy, the system places the subscribers in wait mode until the called subscriber or the required radio channel capacity becomes available.
Traditionally, queuing of calls for radio channel capacity has been realised by establishing an individual queue for each base station of the mobile radio system. Thus, when the base stations required by a call do not have enough radio channel capacity available, the call is placed in wait mode in the queues of these base stations. This has the advantage that when a radio channel of a base station becomes available, a decision may be made immediately to allocate the radio channel to the next call in the queue of the base station. Problems emerge in connection with the known procedure when a channel becomes available at one base station but the call requires channels at one or more other base stations as well. It is then possible that the call is not the first in the queues of these other base stations. In such a case, the call must either reserve the available radio channel and continue to queue for the radio channels at the other base station, or quite simply to continue to queue also at the base station where the radio channel has become available. In both cases, the operation of the system is unsatisfactory. If a call reserves a radio channel beforehand, the radio channel is `useless` for the whole time taken for the call to queue for the other radio channels it needs. On the other hand, if the call does not reserve the available channel immediately, it may need to wait endlessly for the moment when it is the first in all the queues simultaneously.